title: Immunological and clinical consequences of splenectomy in a multiple sclerosis patient treated with natalizumab.
abstract: OBJECTIVE
  Here we report a case of a splenectomized white woman with natalizumab-associated progressive multifocal leukoencephalopathy (PML), occurring as early as after 11 infusions and provide blood fluorescence-activated cell sorting (FACS) analyses before and after natalizumab treatment.
  
  
  METHODS
  This is a report of a single case with immunological studies.
  
  
  METHODS
  Methods comprised neurologic examination, magnetic resonance imaging, and cerebrospinal fluid (CSF) studies as well as immune cell FACS analyses from blood.
  
  
  RESULTS
  Diagnosis of PML was established after positive John Cunningham virus (JCV) DNA was detected in the CSF. An immune reconstitution inflammatory syndrome was treated with repeated cycles of steroid pulses and intravenous immunoglobulins. Reduced numbers of memory B cells, which might play an important role in antiviral immune response, were detected in the blood. Moreover the percentage of CD19+ B cells was elevated in our post-splenectomy patient as compared to a control cohort of multiple sclerosis (MS) patients under natalizumab therapy.
  
  
  CONCLUSIONS
  Splenectomy may increase the risk for the development of natalizumab-associated PML via effects on the B cell compartment. It may be regarded as a risk factor in MS patients independent from the duration of disease.
authors.affiliation: Department of Neurology, Friedrich Alexander University of Erlangen-Nuremberg, Schwabachanlage 6, Erlangen 91054, Germany. Ralf.Linker@uk-erlangen.de.
authors.forename: De-Hyung
authors.initials: DH
authors.lastname: Lee
authors.forename: Anne
authors.initials: A
authors.lastname: Waschbisch
authors.forename: Alexandra B
authors.initials: AB
authors.lastname: Lämmer
authors.forename: Arnd
authors.initials: A
authors.lastname: Doerfler
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwab
authors.forename: Ralf A
authors.initials: RA
authors.lastname: Linker
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000009:adverse effects; D061067:Antibodies, Monoclonal, Humanized / Q000009:adverse effects*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007968:Leukoencephalopathy, Progressive Multifocal / Q000139:chemically induced*; D009103:Multiple Sclerosis / Q000188:drug therapy*; D000069442:Natalizumab; D013156:Splenectomy
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000069442:Natalizumab